Damper mechanism for steering device

Abstract

A damper mechanism includes an outer pipe and an inner member. The outer pipe has first inward convex portions, second inward convex portions, and concave grooves extending along the axial direction and alternately formed in the circumferential direction at the inner periphery thereof. Outward convex portions are formed in the circumferential direction at a plurality of portions on the outer periphery of the inner member. An elastic body is provided between the outer pipe and the inner member. The elastic body includes thick wall portions and thin wall portions. The thick wall portion is provided between one side face of the outward convex portion and the first inward convex portion. The thin wall portion is provided between the other side face of the outward convex portion and the second inward convex portion.

What is claimed is:  
     
       1. A damper mechanism for a steering device, comprising: 
       an outer pipe having inward convex portions and concave grooves extending along an axial direction on an inner periphery side and alternately formed at a plurality of positions in a circumferential direction;  
       an inner member inserted into the outer pipe and having outward convex portions extending along the axial direction on an outer periphery side and fitted in concave grooves between the inward convex portions formed at a plurality of positions in the circumferential direction; and  
       an elastic body provided between the inward convex portions of the outer pipe and the outward convex portions of the inner member, the elastic body including a thick wall portion provided between one side face of at least one of the outward convex portions of the inner member and a first inward convex portion of the outer pipe, and a thin wall portion provided between the outer side face of at least one of the outward convex portions and a second inward convex portion of the outer pipe, wherein the elastic body is configured such that a spring constant increases with an increase in a relative twist angle between the outer pipe and the inner member.  
     
     
       2. The damper mechanism for the steering device according to  claim 1 , wherein: 
       a clearance is defined by the thin wall portion of the elastic body and one of the second inward convex portion and the outward convex portion.  
     
     
       3. A damper mechanism for a steering device, comprising: 
       an outer pipe having inward convex portions and concave grooves extending along an axial direction on an inner periphery side and alternately formed at a plurality of positions in a circumferential direction;  
       an inner member inserted into the outer pipe and having outward convex portions extending along the axial direction on an outer periphery side and fitted in concave grooves between the inward convex portions formed at a plurality of positions in the circumferential direction; and  
       an elastic body provided between the inward convex portions of the outer pipe and the outward convex portions of the inner member, the elastic body including a thick wall portion provided between one side face of at least one of the outward convex portions of the inner member and a first inward convex portion of the outer pipe, and a thin wall portion provided between the outer side face of at least one of the outward convex portions and a second inward convex portion of the outer pipe, wherein the elastic body is configured such that a spring constant increases with an increase in a relative twist angle between the outer pipe and the inner member,  
       wherein the projection height of the second inward convex portion is lower than the projection height of the first inward convex portion.  
     
     
       4. A damper mechanism for a steering device, comprising: 
       an outer pipe having inward convex portions and concave grooves extending along an axial direction on an inner periphery side and alternately formed at a plurality of positions in a circumferential direction;  
       an inner member inserted into the outer pipe and having outward convex portions extending along the axial direction on an outer periphery side and fitted in concave grooves between the inward convex portions formed at a plurality of positions in the circumferential direction; and  
       an elastic body provided between the inward convex portions of the outer pipe and the outward convex portions of the inner member, the elastic body including a thick wall portion provided between one side face of at least one of the outward convex portions of the inner member and a first inward convex portion of the outer pipe, and a thin wall portion provided between the outer side face of at least one of the outward convex portions and a second inward convex portion of the outer pipe, wherein the elastic body is configured such that a spring constant increases with an increase in a relative twist angle between the outer pipe and the inner member,  
       wherein the elastic body further includes a connecting portion for connecting the thick wall portion and the thin wall portion.  
     
     
       5. The damper mechanism for the steering device according to  claim 4 , wherein: 
       a clearance is defined by the thin wall portion of the elastic body and one of the second inward convex portion and the outward convex portion.  
     
     
       6. The damper mechanism for the steering device according to  claim 4 , wherein the projection height of the second inward convex portion is lower than the projection height of the first inward convex portion. 
     
     
       7. The damper mechanism for the steering device according to  claim 3 , wherein the elastic body further includes a connecting portion for connecting the thick wall portion and the thin wall portion. 
     
     
       8. The damper mechanism for the steering device according to  claim 3 , wherein: 
       a clearance is defined by the thin wall portion of the elastic body and one of the second inward convex portion and the outward convex portion.